Github user advancedxy commented on a diff in the pull request:
https://github.com/apache/spark/pull/23083#discussion_r235955118
--- Diff:
core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala ---
@@ -727,9 +727,10 @@ private[spark] class ExternalSorter[K, V, C](
spills.clear()
forceSpillFiles.foreach(s => s.file.delete())
forceSpillFiles.clear()
- if (map != null || buffer != null) {
+ if (map != null || buffer != null || readingIterator != null) {
map = null // So that the memory can be garbage-collected
buffer = null // So that the memory can be garbage-collected
+ readingIterator = null // So that the memory can be garbage-collected
--- End diff --
Hi @szhem , I discussed with wenchen offline. I think this is the key
point. After nulling out `readingIterator`, `ExternalSorter` should released
all the memories it occupied.
Yes, `ExternalSorter` is leaked in `TaskCompletionListener`, but it would
already be stopped in `CompletionIterator` in happy path. The stopped sorter
wouldn't occupy too much memory. The `readingIterator`
is occupying memory because it may reference
`map/buffer.partitionedDestructiveSortedIterator`, which itself references
`map/buffer`. So only nulling out map or buffer is not enough.
Can you try with this modification only and see whether OOM still occurs.
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